In 1998 he was the primary sponsor of an Early Day Motion supporting the repeal of the Greenwich Judgement, which prevents Local Authorities from giving their own residents priority access to school places.[10]

In 2001, he was opposed to government proposals for restrictions on gambling machines, which he described as a “silly bit of nanny state politics.”[11][12][13]

In January 2003, Davey publicly backed local constituent and NHSwhistleblower Ian Perkin, who alleged he had been sacked from his director of finance role for exposing statistics manipulation at St George's NHS healthcare trust.[14][15] Davey condemned the NHS bureaucracy as “Stalinist” and called for an inquiry into Perkin's case,[16][17] while personally meeting trust executives to discuss the case on behalf of Perkin.[18]

Davey was re-elected in the 2001 general election with an increased majority over former Conservative MP David Shaw. He joined the Liberal Democrat frontbench under leader Charles Kennedy in the same year by becoming Liberal Democrat spokesperson for Treasury matters. In 2002, he became the Liberal Democrat spokesperson for the Office of the Deputy Prime Minister. He was appointed Liberal Democrat spokesperson for Education and Skills in 2005 before becoming Liberal Democrats spokesperson for Trade and Industry in March 2006. In December 2006, he succeeded Norman Lamb as Chief of Staff to Sir Menzies Campbell, the party leader.[7] Davey was Chair of the party's Campaigns and Communications Committee. Following Nick Clegg's election as Leader of the Liberal Democrat Party, Davey was awarded the foreign affairs brief, and continued to retain his chairmanship of the party's Campaigns and Communications Committee.[6]

At the 2009 Liberal Democrat conference, Davey caused controversy calling for dialogue with the Taliban, through declaring that it was 'time for tea with the Taliban',[27] a comment echoed by Malala Yousafzai four years later to the BBC.[28]

In late 2012, the Daily Mail published an article questioning Davey's loyalty to Liberal Democrat leader Nick Clegg. Responding in an interview for Channel 4, Davey rejected the claims of the article, saying instead that he thought Clegg was "the best leader" the Liberal Democrats had ever had and that he personally was a member of Clegg's "Praetorian Guard".[50]

In 2013, Davey set up the Green Growth Group, bringing together environmental and climate ministers from across the European Union in an effort to promote growth, investment in renewable and nuclear energy, liberalisation of the European energy market, a global carbon market, trade in energy, carbon capture technology, energy efficiency, and competition.[39][51][52][53][54][55] Domestically, Davey focused on increasing competition in the energy market by removing barriers to entry for smaller companies, and streamlining the customer switching process, declaring in 2013 that “competition works.”[56][57] He also approved the construction of Hinkley Point C nuclear power station.[58] Abroad, Davey promoted investment in the British energy sector by foreign companies including from Japan, South Korea, and China, making significant diplomatic trips to the latter two countries in order to highlight investment opportunities.[59][60][61][62]

In October 2013 during an BBC Newsnight segment on energy bills, in a controversy that was termed by some media as "Jumpergate", Davey was asked by presenter Jeremy Paxman on whether or not he wore a jumper (to stay warm) at home, to which Davey replied that he did but stressed that competition and energy efficiency were the solutions to lowering energy bills. The following day, various media outlets reported that Davey had advised for people to wear jumpers at home to save on energy bills, although he had not. The controversy then spread when Prime Minister David Cameron's official spokesman told a reporter that people may wish to "consider" advice by charities to wrap up warmly, leading to media outlets reporting that Number 10 was also suggesting wearing jumpers to cut energy bills, with the supposed suggestion being seized upon by the opposition Labour Party. Number 10 later issued a statement rebutting the media reports.[63][64][65][66][67][68][69][70]

In April 2014, Davey called for the G7 to begin reduction of dependency on Russian energy following the 2014 Ukrainian revolution and commencement of the War in Donbass.[71] Davey argued the benefits of investment in onshore wind energy from companies such as Siemens was key in the part of the push to reduce dependence on Russian energy,[72] while “more diversified supplies of gas” including from the U.S. and domestic shale gas would also help.[73] In May 2014 at a meeting in Rome, G7 energy ministers including Davey agreed formally to a process for reducing dependency on Russian energy, “Putin has crossed a line” Davey declared.[74]

Throughout and after the Cameron–Clegg coalition, Davey's ministerial career came under scrutiny from political figures and the media. On the Right, Conservatives Nigel Lawson and Peter Lilley were critical of Davey's environmental stances,[75][76] while journalist and climate sceptic Christopher Booker questioned his policy on wind turbines,[77] and he was lampooned by The Telegraph sketch-writer Michael Deacon.[78] He was also criticised by Left-wing figures such as Green MP Caroline Lucas over for his support of fracking,[79] and by Labour Leader Ed Miliband for Davey's warning that Labour's price control policy would cause blackouts.[80] Luxembourgian MEP and environmentalist Claude Turmes alleged in his 2017 book Energy Transformation that Davey's Green Growth Group was actually a front for British nuclear interests.[52] Conversely, Davey's promotion to the role of Energy Secretary was hailed by The Economist which viewed him favourably as a “pragmatic” and “free-market liberal”.[81] In 'The Liberal Democrats and supply-side economics', published in an issue of the Institute of Economic Affairs' Economic Affairs journal, Davey was identified as the Liberal Democrat who had achieved the most in terms of supply-side reforms.[82] Conservative MP and former coalition minister Sir Oliver Letwin credited Davey and his aforementioned “like-minded” group of economically liberal governments as having helped to curb regulatory enthusiasm within the European Union.[40]

Leading up to the 2015 general election, Davey was viewed by various sources as a potential successor to then Liberal Democrat leader Nick Clegg.[83][84][85][86] Political commentator Gary Gibbon speculated that due to Davey's association with the Orange Book wing of the party, the tenuousness of Danny Alexander's parliamentary seat, and David Laws' unwillingness, the role of 'heir' would naturally fall to Davey.[87][88]

At the 2015 general election, Davey was defeated by Conservative candidate James Berry by 2,834 votes after the Liberal Democrat vote fell by over 15% in Kingston & Surbiton.[89] Davey regained the seat for the Liberal Democrats at the 2017 general election, with a majority of 4,124 votes over Berry.[90]

Upon returning to Parliament in 2017, Davey was considered a possible candidate for the Liberal Democrat leadership election following the resignation of Tim Farron. However, he ruled out standing over family concerns, but called on the Liberal Democrats to be “the party of reform” and “super-ambitious -– just like radical centrists in Canada, France and the Netherlands.”[91] Davey is currently the Liberal Democrat Spokesperson for Home Affairs.[92]

He is the Chair of the All-Party Britain-Republic of Korea Parliamentary Group (APPG).[93] He is also the Chair of the APPG on Charity Retail, the Vice Chair of the APPG for the Ahmadiyya Muslim Community, and the Vice Chair of the APPG on Land Value Capture.[94][95][96]

Davey identifies as a liberal politically, telling magazine Total Politics: “I personally think liberalism is the strongest political philosophy in the modern world. Socialism has failed. I think even social democracy . . . is not very convincing, and I don’t really understand where the Conservatives are coming from”.[97] He has said that he believes “in the free market and in competition”,[98] and during a parliamentary public bill committee debate in November 2010 argued in defence of privatisation, deregulation, and the private sector against Labour MP Gregg McClymont.[99] Davey also describes himself as a "strong free-trader", rejecting reciprocity in trade tariffs as "the classic protectionist argument". He believes Britain should be open to foreign investment, except for investment tainted by “smells that you have from Putin."[100] He dismisses worries over foreign ownership and investment in the British economy such as that of Chinese and French companies' involvement in the British energy market.[101][100] Davey considers himself an economist by trade.[102]

He was a supporter of the coalition government, writing in a 2011 column for London newspaper Get West London that the coalition would “restore liberty to the people” and that “Labour's nanny state will be cut back” in reference to the coalition's policies on civil liberties.[103] In 2012 Davey predicted the coalition government would be more pro-European than Tony Blair's Labour government, praising Conservative ministers and the then Prime Minister David Cameron for relations they had developed with European counterparts.[104] Retrospectively, Davey said of the coalition in 2017: “I think the coalition government, when history looks at it, will go down as actually a pretty good government.”[105]

In 2017 Davey warned against a Conservative Party proposal for fines on large internet companies who fail to remove extremist and terrorist material from their platforms within 24 hours, which he claimed could lead to censorship if companies are forced to rush and pointed to Germany as an example of where this approach has the potential to lead to censorship.[106] He thinks technology giants must not be treated as the "enemy" and accused the Conservatives of declaring an "all-out war" on the internet.[106] Similarly he is critical of Conservative proposals to weaken encryption because, according to Davey, encryption is important for individual security and helping businesses to thrive.[107] In 2018, after the government's Investigatory Powers Act (Snooper's Charter) mass surveillance law was declared to be in breach of EU law, Davey commented that UK surveillance needed a “major overhaul” which puts “our freedoms and civil liberties at its very core” (Davey's party opposes the mass surveillance law and had voted against it).[108][109] Since the 2000s, Davey has been vocal on the issue of detention without trial, in particular Guantanamo and Bagram, for which he believed required transparency and formal investigation of torture allegations.[110][111][112] He has opposed indefinite detention for illegal immigrants.[113]

Davey is supportive of market solutions in the conventional energy sector, The Guardian describing him as a 'zealot' for markets. He has been highly critical of price controls such as those proposed by former Labour leader Ed Miliband; he considers them to be detrimental to competition and lowering prices for consumers.[114][100] He has promoted removal of barriers to entry to encourage new entrants into the energy market; “We began with deregulation. This stimulated a doubling of smaller firms” he wrote of his policy as Energy Secretary in 2014.[56][115] Additionally he welcomed the rise of consumer switching websites.[56] He has also been in support of trade to import natural gas from countries including the USA and Qatar,[116][117] and importation of green energy via new interconnectors from Norway and Ireland.[118][119][120] He has, however, supported “properly designed and carefully targeted” short-term subsidies for some emerging green energy technologies in order to meet climate change targets.[121] When cutting green energy subsidies as Energy Secretary, Davey said he “tended to try and marketise the reduction so people were competing for any remaining subsidies” through Contracts for Difference (CfDs).[122] After leaving the office of Energy Secretary in 2015 he explained that he had planned to “eliminate subsidies over the coming years” [123] and had previously stated, “ultimately I don’t want the government—the Secretary of State—to decide what that low carbon mix is . . . I want the markets and technology development and innovation to decide what that mix is.”[100]

He has argued in favour of both nuclear power and shale gas fracking as potential energy sources,[124][125] and natural gases as transitional fuels,[126] though he has warned that there should not be an over-reliance on them.[127][128] Previously in 2006 Davey had argued against nuclear power but in 2013 he urged fellow Lib Dem members to support nuclear power, stating, "I've changed my mind because of climate change."[129]

Davey took up several business appointments after leaving his role as Secretary of State for Energy and Climate Change in May 2015.

Mongoose Energy appointed Davey as chairman in September 2015.[130][131]

Davey set up an independent consultancy in September 2015 to provide advice on energy and climate change.[130]

In January 2016 Davey was appointed as a part-time consultant to MHP Communications, the public relations and lobbying firm representing EDF Energy.[130] Davey was criticised by press commentators for the potential conflict of interest between his previous role as Secretary of State for Energy and Climate Change and his role at MHP. As Secretary of State Davey awarded EDF the contract to build a new nuclear plant at Hinkley Point in Somerset.[132][133]

Davey's appointment as Global Partner and non-Executive director of private equity investor Nord Engine Capital was announced in February 2016.[130][134]

In July 2016 he became non-paid patron of the Sustainable Futures Foundation, a charity promoting environmental sustainability for the public benefit.[130]

Davey married Emily Gasson (Lib Dem candidate in North Dorset) in summer 2005 and their first child, John Alban Davey, was born in December 2007. Their son has speech difficulties, leading to Davey's interest in speech therapy.[135] They live in Surbiton, London; Davey lived there before his election as an MP in 1997. Emily had the number two position on the Lib Dem London-wide candidate list for the 2016 London Assembly elections,[136] but was not elected. Emily then stood for election as a councillor for the three seat Norbiton Ward in 2018, as part of the Royal Borough of Kingston Council and topped the poll with 20% of the vote.[137]